Fans are begging Justin Bieber to cancel his UK tour after the Manchester attack.

Fans of Justin Bieber have pleaded for his coming British tour dates to be cancelled, underscoring the potential repercussions to music acts with a young fan base from the suicide bombing at an Ariana Grande concert in Manchester.

Canadian heartthrob Bieber, 23, is due to play an open-air concert at London’s Hyde Park in July.

But fans flooded social media saying his appearance should be axed for the safety of fans and the singer.

“Cancel Justin’s concert in the UK, please! We want him to be safe, please,” a person using the handle marhrukhh wrote on the Instagram account of Bieber’s manager, Scooter Braun.

Braun also manages Grande, also 23, a former Nickelodeon star whose large female fan base, many of them tweens, were out for her concert in Manchester on Monday night when a suicide bombing killed 22 people and injured dozens.

The singer flew to Florida on Tuesday to spend time with her family, People magazine reported.

Braun and her record company did not return calls on whether the remainder of her world tour, with stops in London and Europe, would go ahead.

This Is What A Leader Looks Like

BONUS: Trump's Very Bad Week

Leanne Murray, 20, who lives in Ireland, has tickets to see Bieber play in Dublin in June.

But she said that after Monday’s bombing she is contemplating selling them.

(Image: Instagram)

"I just don't want what I would hope to be a great night to end in something like last night," Murray, who paid 180 euros ($A269) each for two tickets told Reuters.

Joe Reinartz, of concert industry publication Pollstar, said although he believed security was already strong at music venues and would no doubt be stepped up, parents would likely be more cautious.

"In the short term, there are going to be concerns for any large gathering where there will be young people, and that doesn't necessarily mean a Justin Bieber show. It means a high school football game, or an event at a fair ground," Reinartz said.

Listen: Mamamia Out Loud: We need to talk about Manchester (post continues after audio...)

If you'd like to support the victims of the attack and their families, you can donate to the Manchester attack victims fund here.